pypdf is a free and open-source pure-python PDF library. Prior to 6.21.3, pypdf can consume excessive time and memory when an application accesses the page count of a crafted encrypted PDF whose page tree declares a forged /Count value. Even after successful decryption, page-count retrieval trusts the unvalidated declared count instead of walking the page tree, allowing the attacker-controlled value to drive excessive work and memory use.
This issue is fixed in version 6.21.3.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
None
No additional conditions
Privileges Required
None
No privileges needed
User Interaction
Passive
Minimal interaction
Impact Assessment
Confidentiality
None
No data leak
Integrity
None
No data modification
Availability
High
Complete denial of service
CVSS Vector v4.0
Weakness Type (CWE)
References 4
https://github.com/py-pdf/pypdf/commit/82b91951dc74496bb3efe6465434f041bb6a5e6b
security-advisories@github.com
https://github.com/py-pdf/pypdf/pull/4270
security-advisories@github.com
https://github.com/py-pdf/pypdf/releases/tag/6.21.3
security-advisories@github.com
https://github.com/py-pdf/pypdf/security/advisories/GHSA-62m5-6wh8-28x7
security-advisories@github.com